Ose biljarice (Hymenoptera, Symphyta) u biotopima Kopačkog rita

During 2003, entomological investigations were carried out into the sawflies (Hymenoptera, Symphyta) of Kopački rit Nature Park, supported by the Ministry of Culture, project Insect Research, and by the Ministry of Science, Education and Sports project Entomofauna of Kopački rit. At three groups of stations: inundated, forest and open ground (a total of 8 stations) a total of 220 individuals were sampled selectively with a net and with sticky tablets. From this material, 73 species of sawfly were determined. There is a clear differentiation of the inundated area at which the presence of only 15 species was recorded, but with great abundance, 7 species being recorded only in such kind of habitat (they were recorded only in the inundated area). This investigation also demonstrated that the borderline area between forest and meadow was the best habitat for the sawfly. At this kind of station in Tikveš, the presence of 35 species was recorded.Tijekom 2003. obavljena su entomološka istraživanja osa biljarica (Hymenoptera, Symphyta) na području Parka Prirode Kopački rit uz financijsku potporu Ministarstva kulture (projekt Istraživanje kukaca) i Ministarstva znanosti, obrazovanja i športa (projekt Entomofauna Kopačkog rita). Na tri skupine postaja: poplavnom, šumskom i otvorenom prostoru (ukupno 8 postaja) selektivno mrežicom i ljepljivim pločama uzorkovano je 220 jedinki. Iz tog materijala determinirane su 73 (taksona) vrste osa biljarica. Jasno se razlikuje poplavni prostor na kojemu je zabilježeno prisustvo samo 15 vrsta velike brojnosti, od kojih je 7 vrsta karakteristično za takvo stanište (zabilježene su samo na poplavnom prostoru). I ovim istraživanjem je dokazano da je granično područje šume i livade najbolje stanište za ose biljarice. Na takvoj postaji u Tikvešu zabilježeno je 35 vrsta

Epitaxial growth in dislocation-free strained alloy films: Morphological and compositional instabilities

The mechanisms of stability or instability in the strained alloy film growth are of intense current interest to both theorists and experimentalists. We consider dislocation-free, coherent, growing alloy films which could exhibit a morphological instability without nucleation. We investigate such strained films by developing a nonequilibrium, continuum model and by performing a linear stability analysis. The couplings of film-substrate misfit strain, compositional stress, deposition rate, and growth temperature determine the stability of film morphology as well as the surface spinodal decomposition. We consider some realistic factors of epitaxial growth, in particular the composition dependence of elastic moduli and the coupling between top surface and underlying bulk of the film. The interplay of these factors leads to new stability results. In addition to the stability diagrams both above and below the coherent spinodal temperature, we also calculate the kinetic critical thickness for the onset of instability as well as its scaling behavior with respect to misfit strain and deposition rate. We apply our results to some real growth systems and discuss the implications related to some recent experimental observations.Comment: 26 pages, 13 eps figure

Crop pests and predators exhibit inconsistent responses to surrounding landscape composition

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies

Optimization of RIS-aided MIMO Systems via the Cutoff Rate

The main difficulty concerning optimizing the mutual information (MI) in reconfigurable intelligent surface (RIS)-aided communication systems with discrete signaling is the inability to formulate this optimization problem in an analytically tractable manner. Therefore, we propose to use the cutoff rate (CR) as a more tractable metric for optimizing the MI and introduce two optimization methods to maximize the CR. The first method is based on the projected gradient method (PGM), while the second method is derived from the principles of successive convex approximation (SCA). Simulation results show that the proposed optimization methods significantly enhance the CR and the corresponding MI.Science Foundation IrelandCheck issue date on checkdate -- J

Managing biological control services through multi-trophic trait interactions: Review and guidelines for implementation at local and landscape scales

Ecological studies are increasingly moving towards trait-based approaches, as the evidence mounts that functions, as opposed to taxonomy, drive ecosystem service delivery. Among ecosystem services, biological control has been somewhat overlooked in functional ecological studies. This is surprising given that, over recent decades, much of biological control research has been focused on identifying the multiple characteristics (traits) of species that influence trophic interactions. These traits are especially well developed for interactions between arthropods and flowers – important for biological control, as floral resources can provide natural enemies with nutritional supplements, which can dramatically increase biological control efficiency. Traits that underpin the biological control potential of a community and that drive the response of arthropods to environmental filters, from local to landscape-level conditions, are also emerging from recent empirical studies. We present an overview of the traits that have been identified to (i) drive trophic interactions, especially between plants and biological control agents through determining access to floral resources and enhancing longevity and fecundity of natural enemies, (ii) affect the biological control services provided by arthropods, and (iii) limit the response of arthropods to environmental filters, ranging from local management practices to landscape-level simplification. We use this review as a platform to outline opportunities and guidelines for future trait-based studies focused on the enhancement of biological control services

Magnetic properties of multiferroic K3Cr2Fe3F15

The local electronic and structural as well as the macroscopic magnetic properties of K3Cr2Fe3F15 have been studied between room temperature and 4 K. The system has been found to be isostructural with ferroelectric and weakly ferrimagnetic K3Fe5F15 above the ferroelectric transition temperature T-c. The X-band and 216 GHz Cr3+ electron paramagnetic resonance (EPR) spectra as well as the magnetic susceptibility and Moumlssbauer data show the existence of two magnetic relaxor type transitions around 37 and 17 K. The K-39 magic angle sample spinning NMR, EPR, and the Moumlssbauer data further demonstrate the existence of two nonequivalent Fe, Cr, and K sites in the unit cell as well as the presence of rapid exchange at higher temperatures. The observation of the Fe2+ EPR and Moumlssbauer spectra shows that the Fe2+ ion is in a high spin state